tell her your day was fantastic
you want to be the most interesting thing on the planet, if shes bored with her bf then she will be looking for attention elsewhere, thats where you can come in. but let her come to you, that way you arent percieved as being needy.
be vague and mysterious, keep her guessing
throw in a neg or two, something to the effect of "you and i will never get along"
her "why"
you: "we are too simular, i wont take your shit, you wont take mine, so whats the fun in that.
or
do you always stalk people on facebook?
maybe put the little smilie at the end of this to appear playful.
anyways thats my opinion, good luck